erofs: introduce 'domain_id' mount option

Introduce 'domain_id' mount option to enable shared domain sementics.
In which case, the related cookie is shared if two mountpoints in the
same domain have the same data blob. Users could specify the name of
domain by this mount option.

Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220918043456.147-7-zhujia.zj@bytedance.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index ab746181ae086033849c648b1ceb72382dc222c1..9f7fe6c04e65412e0f736966bbeaded1f1dd0f2c 100644 (file)
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -440,6 +440,7 @@ enum {
        Opt_dax_enum,
        Opt_device,
        Opt_fsid,
+       Opt_domain_id,
        Opt_err
 };
 
@@ -465,6 +466,7 @@ static const struct fs_parameter_spec erofs_fs_parameters[] = {
        fsparam_enum("dax",             Opt_dax_enum, erofs_dax_param_enums),
        fsparam_string("device",        Opt_device),
        fsparam_string("fsid",          Opt_fsid),
+       fsparam_string("domain_id",     Opt_domain_id),
        {}
 };
 
@@ -568,6 +570,16 @@ static int erofs_fc_parse_param(struct fs_context *fc,
                        return -ENOMEM;
 #else
                errorfc(fc, "fsid option not supported");
+#endif
+               break;
+       case Opt_domain_id:
+#ifdef CONFIG_EROFS_FS_ONDEMAND
+               kfree(ctx->opt.domain_id);
+               ctx->opt.domain_id = kstrdup(param->string, GFP_KERNEL);
+               if (!ctx->opt.domain_id)
+                       return -ENOMEM;
+#else
+               errorfc(fc, "domain_id option not supported");
 #endif
                break;
        default:
@@ -702,6 +714,7 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
        sb->s_fs_info = sbi;
        sbi->opt = ctx->opt;
        ctx->opt.fsid = NULL;
+       ctx->opt.domain_id = NULL;
        sbi->devs = ctx->devs;
        ctx->devs = NULL;
 
@@ -846,6 +859,7 @@ static void erofs_fc_free(struct fs_context *fc)
 
        erofs_free_dev_context(ctx->devs);
        kfree(ctx->opt.fsid);
+       kfree(ctx->opt.domain_id);
        kfree(ctx);
 }
 
@@ -916,6 +930,7 @@ static void erofs_kill_sb(struct super_block *sb)
        fs_put_dax(sbi->dax_dev, NULL);
        erofs_fscache_unregister_fs(sb);
        kfree(sbi->opt.fsid);
+       kfree(sbi->opt.domain_id);
        kfree(sbi);
        sb->s_fs_info = NULL;
 }
@@ -1068,6 +1083,8 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
 #ifdef CONFIG_EROFS_FS_ONDEMAND
        if (opt->fsid)
                seq_printf(seq, ",fsid=%s", opt->fsid);
+       if (opt->domain_id)
+               seq_printf(seq, ",domain_id=%s", opt->domain_id);
 #endif
        return 0;
 }

diff --git a/fs/erofs/sysfs.c b/fs/erofs/sysfs.c
index c1383e508bbecf50b877ac1a4b529f0c4807e146..341fb43ad5874f76476c54a824b9b7e29acbd1a6 100644 (file)
--- a/fs/erofs/sysfs.c
+++ b/fs/erofs/sysfs.c
@@ -201,12 +201,27 @@ static struct kobject erofs_feat = {
 int erofs_register_sysfs(struct super_block *sb)
 {
        struct erofs_sb_info *sbi = EROFS_SB(sb);
+       char *name;
+       char *str = NULL;
        int err;
 
+       if (erofs_is_fscache_mode(sb)) {
+               if (sbi->opt.domain_id) {
+                       str = kasprintf(GFP_KERNEL, "%s,%s", sbi->opt.domain_id,
+                                       sbi->opt.fsid);
+                       if (!str)
+                               return -ENOMEM;
+                       name = str;
+               } else {
+                       name = sbi->opt.fsid;
+               }
+       } else {
+               name = sb->s_id;
+       }
        sbi->s_kobj.kset = &erofs_root;
        init_completion(&sbi->s_kobj_unregister);
-       err = kobject_init_and_add(&sbi->s_kobj, &erofs_sb_ktype, NULL, "%s",
-                       erofs_is_fscache_mode(sb) ? sbi->opt.fsid : sb->s_id);
+       err = kobject_init_and_add(&sbi->s_kobj, &erofs_sb_ktype, NULL, "%s", name);
+       kfree(str);
        if (err)
                goto put_sb_kobj;
        return 0;